


Meddling

by Madame_Marian



Category: Ao no Exorcist | Blue Exorcist
Genre: Alternate Universe - Always a Different Sex, Alternate Universe - Gender Changes, But Kinda Just Fun, Female Okumura Rin, Female Rin, Gen, Genderbending, Genderswap, Kinda Crack, Mephisto Actually Cares, Overprotective, Overprotective Brothers, Rule 63, Underage Drinking, too much actually
Language: English
Status: In-Progress
Published: 2020-04-17
Updated: 2020-05-20
Packaged: 2021-03-01 23:14:59
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 5
Words: 6,847
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23695255
Author URL: https://archiveofourown.org/users/Madame_Marian/pseuds/Madame_Marian
Summary: The first thing Mephisto Pheles noticed about his new sister was that she was heartbreakingly adorable. The second thing he noticed was that this was a very, very big problem.In which Mephisto and Co. slowly go mad in an attempt to subtly (or not so subtly, depending on who you ask) protect their only sister from literally everything. But especially boys. Fem!Rin
Comments: 28
Kudos: 370





	1. Chapter 1

The first thing Mephisto Pheles noticed about his new sister was that she was heartbreakingly adorable, to an extent that put all of his beloved moe characters, he was mourn to admit, to shame.

The second thing he noticed was that this was a very, very large problem.

Not now, of course, he had mused as he watched the small child in her first few minutes of life somehow manage to start earning her place as the apple of his eye, not yet. For now, for the next few years, she would be just that- adorable. It was to be expected, after all. Not only was the girl's mother beautiful above most humans in the world, but even if she hadn't been, all children of the royal bloodline came out remarkably attractive. It was part of who they were, and how they emodied seduction to all sorts of different things, physical or no. Seduction to sins. But seduction was exactly the problem he saw awaiting him less than even two decades down the line, curse humans and their ridiculous growth rates!

For even now, he could see all too clearly: Rin Okumura was going to be quite the looker when she grew up. And lookers attracted... boys. And he could not let that stand.

All of these thoughts were kept strictly internal, of course, it wouldn't do to have Fujimoto knowing he may truly care for the child, and on the outside he continued to play the detached cynic, using this as a chance to make a wager he knew would end in his favor. The moment she unlocked her powers, her guardianship would immediately transfer over to him. He estimated this should take a decade at most, even with her power sealed away in kurikara. Satisfied that Fujimoto would, at the very least, keep her from dying or becoming horribly disfigured in the meantime, set off on his merry way, with dark, dark plans already forming in his mind. For her own good, of course.

* * *

"Allow me to make certain that we are on the same page here, Okumura." The man, if he was to be considered that, stated with deadly calm from his place beside the grave of Shiro Fujimoto. The human twin raised an eyebrow with well-deserved caution, and he thought, for a moment, that perhaps it wasn't the greatest of ideas to discuss such things with someone so likely to report back to his beloved sister at the drop of a hat. Then he remembered that he could just threaten him with death and violence. Or worse- expulsion. He didn't have to mean the threats- Yukio would believe him.

"I was most distressed yesterday, you see, as I came to execute your sister. Because, and do forgive my candor, I believe Miss Okumura was wearing..." The demon paused for dramatic effect. "Mascara? And I thought, surely this couldn't be correct, because, what good, religious household allows a CHILD to wear beauty products? A child who, mind you, is very clearly attractive on an unearthly level without such enhancements, and then you allow her to go and do, do... that? Do you know what happens to pretty girls, Okumura? They attract boys. Disgusting, filthy, unworthy boys. So then I thought, well, surely this is some mistake? Surely neither of us want such a tragedy as for our beloved relation to be seduced by a male creature? Surely her brother, who loves her dearly and should wish at all costs to prevent such a scenario for fear of both her safety and his life, would surely remove all such items from her possession in an inconspicuous manner from this point forth? Surely?"

He was expecting an initial refusal, or, at least, a reluctance on behalf of the younger twin, but when the child's blue eyes met his through rain spotted lenses, he could tell that, for the first, and possibly last time in either of their lives, they had found a point of agreement.

* * *

"What the HELL?" The cry wailed the next morning from the upstairs bathroom at the monastery. The shrillness of it was enough to make him wince, but Yukio knew that was the price he had to pay to carry out his duty. And if the garbage that morning happened to contain a little more mascara and blush than usual, he certainly wasn't going to point it out.

"What's wrong, sister?" He called innocently. "Stop fussing about whatever it is and hurry up! Sir Pheles is going to be here to pick us up any minute now."

With the old bathroom door locked firmly shut, she never saw her brother's triumphant smile as he turned away and headed towards the stairs that would lead him to his, as of this moment, only remaining comrade in the war to keep Rin single.


	2. Chapter 2

Rin Okumura had always found it odd and, dare she say, almost suspicious that any boy who showed the slightest of interest in her would miraculously become terrified of her within a week's time. It was almost as though some demonic presence had been watching her from birth just to be certain that he could ward off the slightest chance of her ever having a relationship. Initially, this demonic force was Mephisto.

Being a very busy demon with important demon things to do, he, much to his dismay, had managed to let a few fortunate suitors (if six year olds could be called suitors) slip through the cracks. But as she grew older, and her human brother became more and more aware of how his beloved sister seemed to attract the bad boys like Sir Pheles to an anime convention, their combined evil powers seemed to succesfully lock her out from all non-relational male contact. In fact, with this new revelation of her heritage, she was finding it hard to doubt that her brother didn't somehow inherit selective Satantic powers which arose only at the possibility of her finding a date, and at no other time.

Up to that moment, his had been the only presence which she was securely aware of. But that all changed when she walked into the orientation hall of True Cross Academy and noticed that her uniform was a little... different than all the other girls. About thirteen inches of different, in fact. Whereas the other girls all wore skirts falling somewhere around mid-thigh, depending on height, her tea-length skirt brushed innocently against the middle of her calf, none the wiser to the problem it was about to cause.

"Yukio."

"Yes." Her twin answered dutifully with the look of a soldier who knew he was about to be cut down, but was ready to die for his cause nonetheless.

"Do you have anything to do with this."

"...I don't even know what you mean, sister."

"Don't you play dumb, smart guy!"

"Well would you look at the time, I'm terribly sorry for whatever's troubling you, but I really mujst going, got speeches to deliver and all so-" He dashed out while he still had the chance, leaving the girl alone to find a seat in a sea of high-school shoujo skirts.

"That. DICK!"

* * *

It.

Was.

So.

CUTE.

She stared at the fluffy Scottie before her with unadulterated awe.

"Well helLO!" She cooed in her finest puppy voice. "Who's a pretty baby? Who's a pretty baby?"

The dog wagged it's tail in what she assumed to be approval, as well as giving her smug look that seemed to agree "yes, me, I am a pretty baby", before turning tail and trotting in the opposite direction.

"Wait a second, where are you going, huh?" She whined, following without hesitation.

When they got a suitable distance from the mosh of students, she added the puppy turning into the clown to the long list of disappointments in her life.

"Soft spot for animals, Princess?" The once-dog-now-human shaped school master jested.

"Yeah, real ones, ya freak!" She fumed.

"Well, I am the headmaster of this school, I couldn't very well just be wandering amongst the common folk, now could I?"

She only raised a delicate black-blue eyebrow, pale arms folded over her chest.

"And anyhow, I have important information to share with you regarding your exorcist training."

"Ah, no, hold on a second!" She interjected, unwilling to allow this man to continue without addressing the most pressing issue at hand. "What the HELL is up with my skirt, hm?"

"...A finely dyed linen, imported from the Middle East?"

"The length of my skirt."

Damn her for not being an imbecile.

"Let's think about this rationally, my dear," he drawled, putting on his finest charm. "With those other skirts being so ridiculously short, wherever would you have hidden your tail? As a member of the demonic royal family, the idea alone of you parading about with your tail bared for the world to see, why, I couldn't bare it! How could I allow you to be so classless? The idea of you going on missions and being mistaken by filthy, low level demons as a common whore, when you are are the very princess of Gehenna- why, my heart couldn't take it!"

"Oh," she blinked up at his half-truth. "I guess that makes sense."

"Of course it does!" He internally breathed a sigh of relief. "If anyone asks, just say that your strict religious upbringing led you to seek special permissions about the uniform."

"Yeah, that works!" She grinned up at him with something akin to gratitude and for a moment he thought his heart would melt. Thankfully, he remembered, he didn't have one. What a close call. "Thanks, Mephisto. See, you're not so bad, ya know that?"

"Oh, yes of course," he murmured absently, struggling to keep the pink of his awe off his cheeks. She was just so cute, and sweet, and pure, and... defendable. His own real life tsundere! How lucky was he? "Anyhow, back to the truly important things, I will now show you to the exorcist cram school!"

"A cram school?" She let out in a whine.

"Yes, the exorcist cram school! You will begin as a page, learning the art of exorcism. Your lessons in the primary school don't begin until tomorrow, but your exorcist training begins today!" He waved his hand in a flourish for dramatic effect. "I will take the honor of showing you there immediately. However!"

She flinched as his hand swung out to point scarcely an inch from her face. He resisted the ever so tempting "boop" to her delicate nose, as easy and adorable as it would be, as somehow he found that may make her take his following words less seriously. His restraint was admirable. "Your identity as the daughter of Satan is to be kept and absolute secret! Now, while your tail is already concealed by the skirt as a proper gentle-demon, and your ears and teeth may be explained away, your flames are a different matter. You must keep them under only the strictest control."

A firm line formed over her delicate face that didn't quite succeed in being a serious grimace. "I'll do my best."

He considered her for a moment- considered her eyes that were so superficially similar to their father's, yet set in a genuine expression few had ever known from the original. Very nearly human. Nearly- but something new. "Very well, princess." He spun with a snap, already moving towards their destination. "However I can't help but remain a tad concerned, so I'll be personally monitering this first lesson nonetheless."

This, of course, had nothing to do with staking out the male reaction to her presence in the classroom, or to judge Yukio's worthiness in handling any such reactions. Nothing. At. All.

"Eins, zwei, drei!"

And with that, he was a dog yet again.


	3. Chapter 3

Bon was pretty sure he had never in his life seen anyone more beautiful than Rin Okumura. With her oddly conservative dress, odd sword strapped to her back, and distinctly unladylike mannerisms, she should have been a walking disaster, but instead of the derision he should have been holding in his gaze, he found himself staring in something much more akin to... awe? He wasn't quite sure, all he knew was that whatever it was, it certainly wasn't related to killing Satan, and he didn't like it. Shima, of course, taking the fact that the teacher had yet to arrive as essentially permission to do whatever he pleased, wasted no time in sauntering over to her, draped in his very best bravado.

"Hey pretty lady, the name's Renzo Shima, and you are?" He asked, leaning over onto her desk in his very best image of seductive nonchalance.

She raised one of her dark brows and glanced back at him and Konekomaru as though to say "and why exactly is your pet off his leash and bothering me?". She looked back and hesitated just long enough to make his flirtatious friend start squirming with the awkwardness before finally stating, simply, "It's Rin Okumura."

Taking the response as encouragement, he grinned charmingly. "And what exactly is a girl as pretty as you doing in a rough and tumble kind of class like this, huh?"

Her eyes rolled so intensely at that that is was a wonder they didn't disappear into the back of her head. "This pretty girl is gonna be the best damn exorcist you've ever seen, that's why!"

"Oh really? Tell me more," he patronized. Brimming with his unfounded confidence, Shima reached out in what appeared to be an attempt to brush a stray lock of hair behind her ear, only to instead be met with a rather unexpected attack- but not from Okumura.

"What the fuck, get off me!" The boy screamed, flailing around the room, a small dog with a pink bow latched firmly onto the offending hand. Rin herself was in absolute stitches, gasping for breath through the laughter at his friend's pain. It was beautiful, melodic, he wanted to hear it again- no, no he didn't. He didn't need anything to distract him from his goals, least of all some pretty face with an apparently violent dog.

"Oh god!" She wheezed through the laughter, "That's what you get, ya creep!"

It was at that moment the door finally decided to fling open, and the man he assumed to be their professor walked in. The girl's laughter halted immediately, almost like she'd been choked.

"Yukio?" She breathed out, like she'd thought he was dead for ten years before now.

Ignoring the imperative in her tone, the man, apparently named Yukio, stared, baffled, at the scene before him.

"As of today, I am the professor of this class, Yukio Okumura, and the meaning of this commotion is...?" He trailed off, which something in Bon seemed to register as a threat, though he wasn't quite sure why.

"That chick's fucking mutt attacked me!" Shima accused, pointing at Okumura with the very hand said mutt was still clinging to fiercely.

Okumura stood with enough force to knock her chair back, slamming her hands on the desk. "Because he was being a pervy fucking creep!" She accused back.

"Was not!"

"Was too!'

"Ah. I see," Yukio breathed, and Bon found himself starting to feel a twinge of concern for his friend's well-being. "Well, sounds as though there will be no issues so long as you leave Miss Okumura alone then, will there?" He asked, though his tone indicated the statement was something much more akin to a command. Confusion settling over his face, but clearly wanting rid of the cutesy mutt from hell, Shima slowly nodded his head, as though not sure if that was the right action to take if he wanted to leave with his life.

"Yes, sir."

"Very good, Mr, what was it?"

"Renzo Shima, sir."

"Mr. Renzo. I will remember that."

Somehow, Bon didn't doubt that he would. The dog finally released and returned to its original place at Okumura's desk, and if he didn't know any better, Bon would have sworn the professor and the dog shared a silent nod of approval with one another. But that would have just been crazy. ...Right?

**Notes for the Chapter:**

> Sorry it's a shortie! Amaimon should be showing up next chapter, if that's any consolation lol


	4. Chapter 4

Amaimon had always been fond of dumb, weak, brutish animals. His new little sister was all of those things and cute to boot, so to say he was excited was an understatement.

Sure, he had to admit their fight was a bit of a letdown. If she had been a boy he would have been _so_ disappointed. Certainly, she was the weakest child their father had ever spawned. But she wasn't a boy, and it was a big brother's duty to protect his little sister, so he decided to forgive her.

That being said, she was still so very weak. He told his older brother the second he returned from battle that it was for the best to execute the Rin Protection Plan Operation J- faking her death and locking her away in a tall tower accessible only port key- as soon as possible. For her own good of course. Like, maybe tomorrow. Or right this instant. Ideally yesterday.

His brother, however, had refused him, for some reason this was "a last resort" plan, though Amaimon didn't see why. He didn't bring Behemoth into dangerous battles, so why should he let someone as weak as his imoto go free in a world where nearly everything was clearly a danger? He didn't like it at all.

But what he liked even less was that _woman._ Nasty, horrid, awful woman. Getting between him and _his_ imoto. And just when she'd been starting to show some promise. She had reminded him so much of a little puppy, trying so hard to be so fierce even though it has no teeth. And he was such a good, supportive big brother! Cheering her on, letting her pin him down a couple times. He was really feeling this brother-sister bonding thing, and then she had to go and waste her energy saving a human, and that _woman_ had to show up and stop him before he could break the Kurikara sword (which would have been a perfect excuse to expedite Rin Protection Plan Operation J, he might add). He _hated_ that woman.

And then, even more than the woman, he hated the _boy._ Bon, Rin had called him. This _boy_ who seemed to think he had the right to talk to his imoto, laugh with her, eat her cooking, this _boy_ who, unlike the pink-haired child, she didn't push away when he stood a little too close for comfort. Filthy, filthy, _unworthy_ boy.

He watched as they interacted beneath him, his sister and her classmates, arranging tents, laughing, playing human. But his imoto wasn't human, she didn't belong with them, she shouldn't _be_ there. She should be home, safe, in Gehenna, where her brothers could protect her from _creatures_ like these human boys. He chewed on his nail with a growing intensity, vaguely aware that his brother was rambling on behind him.

Mephisto, for his part, was equally disgusted by the bond he saw growing between his darling little sister and this "Bon" child. No boy was worthy of their little sister, of course, but _human_ boys weren't worthy of so much as laying eyes on a photograph of her from the other side of the world and frankly the fact that they were allowed to exist in the same room as her was disgusting.

"Aniki, I think that rooster boy thinks has the right to court our imoto," Amaimon observed. His face was passive as ever, but his tone carried something of a threat in it. Good.

Mephisto let out disgusted noise, followed by a barely repressed shudder. The idea that any human could ever think themselves worthy of _his_ imoto, made him want to cast the entirety the planet Earth into flame, which was appalling because Japan was on planet Earth, but that was just the kind of senseless rage such vulgar thoughts brought him. "I hate to say it, brother, but I think you may be correct. As much as I would generally prefer you not to maim or kill my students, I fear for this case I must make an exception."

"Oh?" He asked, interest piqued nearly as much as if he had offered him a piece of candy.

"Yes. It seems our _human_ brother is not adequately carrying out the protection duties I assigned to him, so it is your duty now, little brother. Please do refrain from _killing_ the boy, though." He narrowed his eyes to cruel slits. "For now."

* * *

The boy, the _boy,_ nasty filthy _boy_ , had his little sister seated on his shoulders. The disgraceful, _human,_ unclean, _boy_ had his head sandwiched between the thighs of _his_ only imoto. _His_ imoto.

He heard a distinct ' _snap'_ to his right, and recognized vaguely that his brother had snapped one of his frilly parasols clean in half.

"Amaimon."

"Yes, Aniki?"

"You may kill the boy."

* * *

" _You_ are the human who thinks he has a right to lay hands on _my_ imoto," Amaimon accused, tightening his group on the rooster boy's throat.

"I don't know what you're talking about," the boy sputtered under his grip, feet flailing wildly as he attempted to free himself.

"Let him go, you bastard!" He easily side-stepped the swing of his sister's still sheathed sword, shooting her a wild-eyed glare in response. She let out a small gasp as their eyes connected, the demon in her surely recognizing the command to stay back, but his imoto was never all demon, was she? She hesitated, not long, but just enough for him to easily stamp her beneath his boot before she could complete the second swing of the blade she had raised over her head.

"Now now, imoto, your big brother can't play right now. I'm taking care of something important here," he chided.

"Let. Bon. Go." She demanded, even from under the heel of his boot, flames she was desperately trying to hold back just creeping into the edges of her eyes. His frown only deepened.

"It seems you are fond of this human. Sorry, imoto, big brother and I are in agreement that human suitors are not acceptable, so he has to go. Besides, you're much too young! Don't worry, I'm sure you can find a new toy, maybe when you're, say, 500 or so."

"I don't know what the hell kind of bullshit you're going on about," she growled, gripping her sheath with a determined look blazing in her eyes, "but what I do know is that I will _not_ let you hurt my friends!"

"Hmm. Too bad~! _You_ don't have the power to stop me!"

"Not like this I don't," she agreed, "but how about-" she ripped the blade from its sheath, setting her and the forest near her alight in a stunning blue, "-like this!" She swiped his foot away with the flaming blade, and used his surprise at her proactive transformation as an opportunity to grab the boy by the back of his collar and wrench his from her brother's grasp.

"R-rin? What the hell is this!?"

"Sorry." She shot the boy a sad smile. "But I've got it from here."

"Oh no, imoto!" He whined. "This is no good, you're much too pretty like that! The more you make yourself pretty, the more of your friends I'll have to kill. You're far too young to be looking for suitors like this, imoto!"

Ignoring his ramblings, she tossed the boy towards his other friends who had incapacitated earlier. "Get as far away from here as you can!" She commanded them. Shooting them one last longing glance, she positioned herself between himself and the boys, crouching into a fighting stance. "Apparently I have some brotherly ass to kick."

* * *

The fact that his imoto was not only powerful but, in fact, more powerful than himself even, was a development that, for Amaimon, caused many conflicting feelings.

On one part, he hated losing in battle, _hated_ it, more than he hated that _woman,_ and even more than he hated that _boy._ Well, maybe. He'd have to come back to that one.

But, on a slightly bigger part, he was... relieved? Yes, something in him was brought some level of happiness by knowing that his little sister could handle herself after all. This certainly reduced his and his brother's workload by a fair deal, if she could keep away unwanted suitors by herself. Now those suitors she _did_ want though, well.

Those were what having eight older, demonic brothers were for.

**Notes for the Chapter:**

> Oh my god. I was not meant to write Amaimon. Like, I hope y'all still enjoyed this chapter but I was NOT meant for it. I went through 3 full length, entirely unique versions of this chapter. I even posted one of them for all of 2 minutes. I cannot wait to write from a Mephisto-based perspective again, he's SO much easier lol. I hope I still managed to make something entertaining here anyways!!
> 
> Next chapter is in the works and contains some fun and very not-brother-approved developments in Rin's life experiences.


	5. Chapter 5

Rin had been waiting for this day for pretty much the entirety of her teenage life.

The circumstances would never be more perfect. Yukio was out of town for two whole days on a mission, and Shura left to go home and/or presumably get passed out drunk at promptly 9pm most weekdays, leaving her completely unsupervised from 9pm to whenever Shura decided to drag herself out of bed the next day. Usually around noon. This meant the entire basically abandoned dorm building which was usually occupied by herself and her brother was now left entirely to her, for her to use however she pleased, and no one could stop her, least of all her own nearly non-existent sense of self-preservation.

Rin Okumura was gonna throw a bangin' party.

With a hearty amount of persistence on her part, she managed to convince everyone that this was a fantastic idea. Well, maybe not quite _fantastic,_ but the point was that everyone was coming. They had had a rough time recently, after all! First with the whole Impure King deal over in Kyoto, and then with that squid monster. The latter had been more remarkable than it should have been since it had resulted in Rin wearing a swimsuit. She hadn't thought twice about it until Shima took it as an invitation to be even touchier than normal, which consequently resulted in Yukio shooting a bullet through one of said touchy hands. He claimed his finger slipped, but all the boys gave her a wide berth for the rest of the mission nonetheless.

Anyhow, the point was they all deserved to relax and let loose a little. Which is why, in exchange for a small mountain of gourmet treats and a promise of more to come in the following weeks, Kuro had given her access to a small portion of his stash of silver vine sake.

Giggling to herself at her own brilliance, she riffled to the bottom of her underwear drawer and pulled out the rather large container of sake and then, even more dangerous than that, a pair of shorts. _Short_ shorts, to be precise.

Now, it wasn't like she wanted to wander around dressed like the old bag all the time or anything, despite what Yukio seemed to think she was far from _promiscuous._ But sometimes she wanted to wear clothes that didn't fall in line with a Catholic girl's school dress code, like shorts more than three inches above the knee, or a shirt that exposed- _gasp-_ her upper collarbones. Besides, she was a young girl! So what if she _did_ want boys to think she looked cute? It wasn't like she couldn't beat them off if she wasn't interested.

And so it came to be that at 10pm that night the cafeteria of her dorm was filled with all of those she had come to call friend over the past year or so of cram school, laughing, passing the sake, having a good time. She wore her short-shorts with no brother around to chastise her for them, and maybe she noticed Bon looking at her legs, and maybe she liked it. Maybe the booze was going a little to her head, and maybe she decided to actually flirt with him a bit while she had the chance. So what? Tonight, no one could stop her. Tonight, she had everything under control and accounted for, and she could do whatever she wanted.

Everything accounted for.

Except, well, there was just _one_ little thing she may have forgotten about.

Ukobach may have been her friend after the Great Kitchen Battle of 2011, but at the end of the day he wasn't _her_ familiar. Oh no.

He was Mephisto's.

* * *

It wasn't that Mephisto had _no_ trust in his littlest, human brother to look after their only sister. No, it was just that he had very _little_ trust.

So, enter Ukobach, who was under strict orders to report immediately back to Mephisto should Yukio fail in any such brotherly duties. Especially relating to boys.

As such, when Ukobach turned up in Mephisto's office and interrupted his 47th marathon rewatch of Lucky Star, he knew things had to be serious.

"A party you say!?" The demon exclaimed. "Rin in _booty shorts_ you say!? Flirting with a _**BOY** _you say!?"

That was all the information he needed. It was a real shame, he had never _wanted_ to have to personally murder one of his own students, but desperate times call for desperate measures. Horrible measures. _Violent_ measures.

He jammed the port key to his sibling's dorm into the door of his office with a little more force than necessary, and ripped the it open as he turned the knob, amazed that he didn't break it off the hinges. What he saw when he opened that door made him freeze. This was his worst nightmare. No, worse than his worst nightmare. Worse than the nightmare worse than his worst nightmare!

The scene before him was one typical of human teen debauchery. Teens in casual clothing were spread around the room, faces flushed with varying stages of intoxication. This isn't what disturbed him, oh no, at this point he WISHED Rin had been passed out drunk like the Shima boy, what she was actually doing was much, MUCH worse.

His little sister, his _only_ sister, his pure, adorable, untainted imoto, was dressed in the heinous invention known as _short shorts_ , tail exposed to the world, and then, even worse than that, she sat straddling the "Bon" boy's lap, arms wrapped loosely behind his head, with their lips locked in that filthy human custom known as a _kiss._

Well. He knew this day would come sooner or later. It was time to execute Rin Protection Plan Operation J.

He knew he should have made True Cross a girl's only school the second Rin was accepted/forcibly enrolled by yours truly. It would have been a hard sell, but he could have swung it with the Vatican if he came at it from the right angle. Now look what's happened. A boy's about to be dead.

"Um, Rin, Bon? I think you might wanna cut that out now..." Konekomaru, the only one of the group that appeared to be sober, tugged at the sleeve of his sister's shirt.

"Huh?" She pulled away to turn her head to the boy and he finally got a good look at his sister's face, flushed a deep scarlet with intoxication. "Wha the hell are ya talkin' 'bout?" She slurred.

The boy merely pointed in the direction of the doorway where Mephisto stood, still frozen in horror.

"HUH?" She exclaimed, making no effort to move from her current position. "The hell are you doing here, clown!?"

Bon, for his part, went from being cast pink with a mixture of alcohol and embarrassment to being white as a sheet with impressive speed. "Get off, Rin!" He demanded in a desperate last bid for his safety.

"Why the hell would I do that, huh?" She leaned in closer and shot the headmaster a suitably devilish look out the corner of her eye. "I'm comfy here."

"So you and Rin are on a first-name basis, then, Suguro Ryuji?" Mephisto asked in a tone that made Bon feel like it might be for the best if he went ahead and slit his own throat to save the other the trouble. Would probably be a lot less painful, too.

"Well-"

"What of it!? Clown." Rin demanded, still not removing herself from the boy's lap. Which, to be honest, might have been the only thing keeping him alive at this point.

In a rare show of anger, Mephisto crushed the door-knob in his hand flat. "Rin. Remove yourself from the human."

"Why doncha MAKE me?" She mocked, sticking her tongue out at him childishly.

"Fine. If you want to play that way, then I will."

"Huh?" She blinked, and the next thing she knew she was in... some kind of... void?

"Oh my!" She heard a familiar voice call from over her shoulder.

"Oh no."

"What are you doing here, imoto?"

"Why the fuck are _you_ here, Amai-whatever!?"

"Hm." The green-haired boy placed a finger on his chin in thought. "Well that's not very nice." He floated closer, taking a good look at her face, wrinkling his nose as he caught a whiff of her breath. "Ah, I see! You're drunk!"

"What of it, Amai-ma-min- whatever the hell your name is."

"It's Amaimon, but I already told you, you can call me nii-san!" He informed her in a tone that resembled cheer. "I wonder what you did to make older brother throw you in here. It must have been pretty bad~"

"I don't know what the hell you're talkin' 'bout," she insisted. "All I did was throw a party and make out with Bon and the clown lost 'is damn mind."

The grin on Amaimon's face dropped so suddenly that if it had been tangible, and they hadn't been floating in an endless void, it would have shook the floor with a resounding thud. "Sorry, imoto, I must have heard you wrong, because it sounded like you said you kissed the rooster boy."

"Rooster boy?" She asked, exploding into laughter. "Ah, that's fuckin' funny, Amiamomo, I'll give ya that one."

"This is no funny matter, imoto!" the demon king protested. "Tell me I misheard you!"

"Hm? But you didn't. What, are you gonna get mad about it too?"

Amaimon didn't acknowledge her, instead turning towards the depths of the void. "Aniki!" He shouted pointlessly. "Let me out! It's not fair if you get to kill her suitor all by yourself! I'm her older brother too! Aniki!"

Not sure what most of that spiel was about, but very on board with the 'let me out' part, Rin joined in on the shouting. "Yeah, Clown!" She cheered. "Lemme out!"

"ANIKI!"

* * *

Meanwhile, outside the void, the esquires were fairing little better than their trapped classmate. One second Rin was there, lounging on Bon's lap like queen of the castle, and then she wasn't, leaving only a fuming Mephisto behind, holding Bon up effortlessly by the collar.

"Since I am a kind and benevolent headmaster, Ryuji Suguro, I will give you 10 seconds to tell me why I should not kill you where you stand."

"She kissed me first, I swear!"

"Like I would ever believe that! My darling imo- I mean charge, would never do something so vulgar."

"No, headmaster, he's telling the truth!" Konekomaru shouted in defense of his friend.

Izumo watched the situation unfolding before her with a sigh. Everybody who was anybody knew that Mephisto Pheles was a demon king, aka one of Rin's many older brothers. One of the more powerful ones, too. You'd think someone as old and powerful as _Samael_ would be above pettiness like bullying human boys for fraternizing with his little sister, but apparently wisdom and age really didn't correlate after all.

"Headmaster." She said dispassionately, wondering in the back of her mind why she continues to stick her head out for these losers. At least this time she could blame the booze. The demon's eyes shot over to her, but his grip on the boy's collar didn't waver. "He's telling the truth. Rin really did kiss him first. I'm sure Bon has no ill intent towards her, sir."

"And what do you know of his intent?" Mephisto borderline hissed. Wow. Izumo barely restrained a severe eyeroll. This was _ridiculous._

"He _is_ an aspiring monk, sir. He's very focused on his duties, and not much else. He's _so_ one-track mind about his whole 'killing Satan' thing, it's honestly irritating. I doubt he even notices that Rin's a girl at all."

"Are you calling my imo- my CHARGE, boyish!?'

Izumo couldn't _believe_ the stupidity she was witnessing tonight. "No sir, that's all Bon's tunnel vision, nothing to do with Rin at all."

"Hmm." Mephisto squinted aggressively Bon's face, searching for any spec of guilt. Unfortunately, the only prevalent emotion on the boy's face was terror. He knew what the Kamiki girl was trying to do, he _was_ a demon king, after all. If Shura's flirtiness couldn't pull one over on him, this inebriated 15 year old certainly couldn't. Still, he really did prefer not to _kill_ his own students if he could suitably inspire distance with a fear of death just as well. And this boy _did_ keep his sister alive in Kyoto, not that he would have ever let her actually get hurt of course. Mephisto, in his infinite generosity, decided this, combined with the slight uncertainty of the whole situation, was just enough to let the boy live... for now.

Mostly because he didn't want to deal with his sister's outrage if he actually killed a human, really.

"Alright." He placed the boy on the floor and released his shirt, which now tented oddly around the collar from his grip. "Consider this your one and only warning, Ryuji Suguro." He flashed a grin that he knew emphasized his inhuman canines. "Get a second strike and you're out, hm?"

"Y-yes, headmaster," he agreed reluctantly, but looking suitably shaken for now.

"Very well. You all go back to your respective dormitories now, I'll deal out your respective punishments in the morning." He watched as the grumbling student body stumbled out of the room, all desperate to be the first to leave, the Shima boy's still unconscious body thrown over Bon's shoulder like a sack of potatoes.

With a sigh, he summoned the cuckoo clock that contained his infinite prison and opened the door to outraged screams of "Aniki!" and "Clown!", respectively. What he wouldn't give for his little sister to call him "Nii-san" like his beloved moe characters instead of her rude nicknames, be he supposed that required her actually figuring out that they were related, which he doubted would happen until someone told her directly.

He sighed again, freezing the both of them so that Amaimon didn't rush out and do something brash, dragging his sister out by the nape of her shirt like the mother of a disobedient puppy. Which was not entirely unlike how he was feeling at the moment.

"Tomorrow, imoto," he said, dropping her into her unmade bed in the room beside her brother's, "you and I are going to have a _long_ conversation."

He gave her one uncharacteristic knock to the head to make sure she stayed konked out, as he really couldn't deal with her right now, especially drunk off her ass like she was at the moment. He thought about just leaving her like that, she was half-demon after all, it wasn't like she was going to catch a cold. He sighed. How lucky that he had had only brothers to this point, if sisters made him this soft. His father should learn to keep it in his damn pants if this was a possibility. He really couldn't handle more than this.

Knowing that if anyone saw him he would never be able to hold his head with pride again, he gently pulled the blankets over his sleeping (ie knocked the fuck out) sister, and then, deciding that wasn't good enough, tucked them in for good measure.

"Sleep well, little sister," he said, making his way to the door, "Your other brothers and I are about to have a long strategy meeting, and you aren't going to be happy about its results. Someday you'll thank us."

Probably.

* * *

The following day Rin got the feeling that perhaps her party hadn't been the best idea after all. She wasn't sure why at first, her memories lost somewhere in the smoky haze of her hangover, but for some reason her stomach was knotted in a whole lot of dread and she didn't appreciate it.

She got ready and went about her day as usual, blissfully unaware of the events of the previous night until she was walking down the hallway and made eye-contact with Bon in passing. Bon. For some reason, she felt like something significant had happened with _Bon_. With a gasp, it all came rushing back to her, from when she had kissed him (which he kissed _back_ , she would like to point out), all the way up to being thrown into some void where Amaimon also was for some reason.

Both parties froze. "Bon." She stated simply.

"Rin."

Uh-oh.

Yukio was going to _kill_ her.

That is, if he didn't kill Bon first.

**Notes for the Chapter:**

> Had fun writing this one. Poor Bon, he had no idea what he was getting himself into

**Author's Note:**

> Posted to FF a long as time ago, figured I might as well upload SOMETHING to my AO3 after years of having it


End file.
